21939419 has 2 divisors, whose sum is σ = 21939420. Its totient is φ = 21939418.

The previous prime is 21939391. The next prime is 21939439. The reversal of 21939419 is 91493912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21939419 is a prime.

It is a super-2 number, since 2×21939419² = 962676212115122, which contains 22 as substring.

It is a Chen prime.

It is equal to p_1385678 and since 21939419 and 1385678 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21939439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10969709 + 10969710.

It is an arithmetic number, because the mean of its divisors is an integer number (10969710).

Almost surely, 2^21939419 is an apocalyptic number.

21939419 is a deficient number, since it is larger than the sum of its proper divisors (1).

21939419 is an equidigital number, since it uses as much as digits as its factorization.

21939419 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 38.

The square root of 21939419 is about 4683.9533516037. The cubic root of 21939419 is about 279.9464991317.

The spelling of 21939419 in words is "twenty-one million, nine hundred thirty-nine thousand, four hundred nineteen".